Communication networks coupling input and output devices have been increasingly applied to a many different control systems. Weld controllers are no exception. There are a variety of different fieldbus communication protocols, including Interbus-S, Ethernet and Profibus. These input devices and output devicesallow the controllers to receive and process local I/O functions such as isolation contactor control, auxiliary contactor feedback control, shunt trip, and control stop. These protocols are usually dedicated to a given weld controller or to a network of weld controllers having the same type of control. With a production line having different types of contollers and operator interface units coupled to different networks, it becomes difficult to determine which unit is being controlled over which type of network. Each weld controller would require a different network interface unit for each different I/O protocol because of a mix of dissimilar data structures on the different networks. It would be preferrable to have a network interface unit to the weld controller system that will allow for the interchangeability of field bus protocols independent of the weld controller functionality by utilizing a common fieldbus to network module interface and the network module to weld controller interface and one that is generally adaptable to resistance welders utilizing a variety of control strategies regardless of the types of data handled by each welder.